﻿#region Copyright information
// 
// Copyright © 2005-2013 Yongkee Cho. All rights reserved.
// 
// This code is a part of the Biological Object Library and governed under the terms of the
// GNU Lesser General  Public License (LGPL) version 2.1 which accompanies this distribution.
// For more information on the LGPL, please visit http://bol.codeplex.com/license.
// 
// - Filename: FagerMcGowan.cs
// - Author: Yongkee Cho
// - Email: yongkeecho@gmail.com
// - Date Created: 2012-09-06 11:39 AM
// - Last Modified: 2013-01-25 3:59 PM
// 
#endregion
using System;
using System.Collections.Generic;

namespace BOL.Linq.Distances
{
    public static partial class Similarity
    {
        /// <summary>
        /// Fager & McGowan = Ochiai - 0.5 * max(a + b, a + c)
        /// </summary>
        public static double FagerMcGowan(this IEnumerable<bool> first, IEnumerable<bool> second)
        {
            var bc = first.BinaryCardinality(second);

            return bc.Item1 / Math.Sqrt((bc.Item1 + bc.Item2) * (bc.Item1 + bc.Item3)) - 0.5 * Math.Max(bc.Item1 + bc.Item2, bc.Item1 + bc.Item3);
        }
    }
}
